Refrigerator



Feb.

26, 1963 A. A. BROS 3,078,683

REFRIGERATOR Filed May 15, 1961 AGEN1 United States Patent Ofiice 3,978,683 ti' alented Feb. 26, 1963 3,078,683 REFREGERATOR Albert August Dros, Emmasingel, Eindhoven, Netherlands, assignor to North American Philips Company, Inn, New York, N.Y., a corporation of Delaware Filed May 15, 1961, Ser. No. 126,743 Claims priority, application Netherlands May 30, 196i) 3 Claims. (6i. 62-6) This invention relates to a refrigerator which comprises a compressor, and an expansion piston that is movable in a cylinder. The refrigerator according to the present invention is characterized in that, whereas the compressor and the cylinder in which the expansion piston is movable are connected together by means of a couple of tubes for the working medium which invariably is in the gas phase, the expansion piston, which is associated with the cycle of the refrigerator, is constructed as a double-acting piston. The surface of the double-acting piston remote from the expansion chamber of the refrigerator varies an additional space which serves as an additional compression stage for the workingmedium of the refrigerator flowing from the compressor to the expansion chamber. A primary advantage of such a refrigerator consists in that the possibility exists to provide the compressor and the cylinder in which the expansion piston is movable at a definite distance from one another. As a matter of fact, these two parts need only be connected by means of a couple of tubes for the working medium. Notably, the operating mechanisms of the compressor and of the expansion piston may structurally be separated from one another.

Another advantage of the refrigerator according to the invention consists in that the mechanical work which becomes available on expansion of the working medium in the chamber in which the expansion piston is movable, is effectively used. As a result of this, the working medium from the compressor is further compressed. Because the two sides of the double-acting expansion piston move in opposite phases, it is necessary to provide controlled stop members, such as valves or slide valves in the connection tube between the additional compression chamber and the expansion chamber of the refrigerator. The expansion and compression cylinder combined in this manner has the advantage that during operation it is self-controlling.

An additional advantage of the refrigerator according to the invention consists in that the chamber which, in practice, must be available below the expansion piston in order to check leakage losses of gaseous working medium from the expansion cylinder and to serve as a buffer chamber below the expansion piston, is etfectively used in the refrigerator according to the invention as an additional compression chamber.

It will be clear that the compressor utilized in the refrigerator according to the invention may be either a piston compressor or a rotating compressor.

In order that the invention may be readily carried into effect, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawing, in which:

The reference numeral I is the compressor constructed in this case as a piston machine. The reference numeral 11 is the combined unit of the expansion chamber and the additional compression chamber.

The piston machine I comprises a cylinder which is provided with automatically opening and closing discharge and suction valves 1]; and 12 respectively. The compression piston 13 is movable in the cylinder 10 by means of a gear not shown.

The unit ll comprises a diagrammatically shown cylinder 14 in which the double-acting piston 15 can move up and down. This piston is provided with a piston rod 16 which is passed through the bottom 1'7 of the cylinder ltd by means of a stufiing box. The piston rod 16 is connected to a connecting rod 19 through a crosshead 18. The rod 19 is connected to a crank 24? which in turn forms part of a crankshaft 21.

The cylinder 14 has two spaces changing their volumes in opposite phases, namely the space 2 2 over the piston 15 and the space 23 below the piston 15. The space 2-2, which in this case also contains a regenerator 24 and a heat exchanger 25, is provided with a controlled supply valve 26 and a controlled exhaust valve 27. The space 23 below the piston 1d comprises an automatically opening and closing suction valve 28 and discharge valve 29.

The exhaust of the cylinder 19 empties through the compression valve 11 in a tube 3i) which includes a cooler 31. The object of the latter is to admit the gaseous working medium compressed in the compression cylinder It) to the space 23 through the valve 28 in a cold condition. The above-mentioned space empties into an additional tube 31:; in which also a cooler 32 is arranged. The tube 31a supplies the gas flowing in the tube 31a to the space 22 in the cylinder 14 above the piston 15 through the valve 25 in a cold condition. Finally, at the exhaust through the valve 2'7 of the space 22, a tube 33 is available which again supplies the working medium to the compressor cylinder ill through the suction valve 12.

During operation of the refrigerator, the gaseous Working medium, for example, helium, which, for example, is at room temperature, is compressed in the compressor cylinder 10 and supplied to the space 23 in a compressed condition, part of the heat supplied to the medium on compression being withdrawn in the cooler 31. The compressed medium is further compressed in the space 23 and in this condition supplied to the expansion space 22 through the cooler 32. By a suitably chosen timing of opening and closing of the valve 2 6 it is achieved that at the instant at which the compressed medium enters the space 22 through the valve 26, the piston 15 is near its top position. The piston 15 is moved downwards by the expanding working medium and at the same time the medium in the space 23 below the piston 15 is compressed. During the last part of the descending stroke of the piston 15, the valve 26 is closed. At the end of the descending stroke of the piston 15, it ascends again as a result of the presence of a flywheel on the crankshaft 21 not shown. When the piston 15 ascends, the expanded gaseous medium is removed from the space 22 and finds its way through the valve 27 to the compressor again through the tub 33.

On expansion of the gaseous wor ting medium in the space 22, the medium passes through the regenerator 24, in which it leaves part of its heat. As a result of the cooling of the medium during the expansion, the heat exchanger 25 is cooled, so that another medium flowing on the outside of the freezer 25, may be cooled by it. So here the contemplated refrigeration takes place.

When the medium leaves the space 22 and flows to the compressor, it again takes up part of the heat from the regenerator.

In the refrigerator according to the invention, the advantage is obtained that the expansion power which is released when expanding the medium in the expansion chamber 22 is at least partly used effectively to compress the working medium additionally. So the expansion piston need not be provided with an additional brake, since the double-acting piston present in the combination of the expansion chamber and the additional compression chamber is self-controlling.

The device according to the invention has the particular advantage that the units I and II need be connected together by means of a couple of tubes only which may be flexible, if desired, and may consequently be provided at some distance from each other, if desired.

While I have shown and described the preferred embodiment of my invention, it will be understood that the latter may be embodied otherwise than as herein specifically illustrated or described and that in the illustrated embodiment certain changes the detaiis of construction and in the arrangement of parts may be made without departing from the underlying idea or principle of the invention within the scope of the appended claims.

What is claimed is:

l. A refrigerator comprising a first cylinder having a compression piston reciprocating therein and .1 second cylinder with an expansion piston reciprocating therein and part of said second cylinder being an expansion chamber having a regenerator therein, and another part of said cylinder being a compression chamber, a pair of tubes connecting said first and second cylinders forming a closed system having a Working medium therein, an additional tube connecting one end of said second cylinder with the other end thereof, said expansion piston being double-acting and having its surface remote from the expansion chamber of the cylinder varying the volume of a space connected to the additional tube which serves as an additional compression stage for the Working medium flowing from the compressor through the expansion chamber of said refrigerator, said expansion chamher being provided with inlet and outlet valves and said compression chamber being provided with a plurality of check valves.

2. A refrigerator comprising a first cylinder having a compression piston reciprocating therein and a second cylinder with an expansion piston reciprocating therein and part of said second cylinder being an expansion chamber having a regenerator therein, and another part of said cylinder being a compression chamber, a pair of tubes connecting said first and second cylinders forming a cicsed system having a working medium therein, an additional tube connecting one end of said second cylinder with the other end thereof, said expansion piston Being double-acting and having its surface remote from the expansion chamber of the cylinder varying the volume of a space connected to the additional tube which serves as an additional compression stage for the working medium flowing from the compressor through the expansion chamber of said refrigerator and a regenerator and heat exchanger in said second cylinder which permits expansion of the medium and cooling thereof, and the s ure of the medium on the other side of said double 'ng piston, said expansion chamber being provided with inlet and outlet valves and said compression chamber being provided with a plurality of check valves.

3. A refrigerator as claimed in claim 1 wherein one of said pair of tubes is providcdwith a cooler while said additional tube is also provided with a cooler.

Re erences Cited in the file of this patent UNITED STATES PATENTS Van Hecckeren Oct, ll, 1949 Kohler Oct. 21, 1958 

1. A REFRIGERATOR COMPRISING A FIRST CYLINDER HAVING A COMPRESSION PISTON RECIPROCATING THEREIN AND A SECOND CYLINDER WITH AN EXPANSION PISTON RECIPROCATING THEREIN AND PART OF SAID SECOND CYLINDER BEING AN EXPANSION CHAMBER HAVING A REGERERATOR THEREIN, AND ANOTHER PART OF SAID CYLINDER BEING A COMPRESSION CHAMBER, A PAIR OF TUBES CONNECTING SAID FIRST AND SECOND CYLINDERS FORMING A CLOSED SYSTEM HAVING A WORKING MEDIUM THEREIN, AN ADDITIONAL TUBE CONNECTING ONE END OF SAID SECOND CYLINDER WITH THE OTHER END THEREOF, SAID EXPANSION PISTON BEING DOUBLE-ACTING AND HAVING ITS SURFACE REMOTE FROM THE EXPANSION CHAMBER OF THE CYLINDER VARYING THE VOLUM OF A SPACE CONNECTED TO THE ADDITIONAL TUBE WHICH SERVES AS AN ADDITIONAL COMPRESSION STAGE FOR THE WORKING MEDIUM FOLLOWING FROM THE COMPRESSOR THROUGH THE EXPANSION CHAMBER OF SAID REFRIGERATOR, SAID EXPANSION CHAMBER BEING PROVIDED WITH INLET AND OUTLET VALVES AND SAID COMPRESSION CHAMBER BEING PROVIDED WITH A PLURALITY OF CHECK VALVES. 